Resilient supports

ABSTRACT

A resilient support ( 10 ), such as for supporting part of the exhaust system of a motor vehicle, is molded from elastomeric material such as rubber. Upper and lower end blocks ( 16, 18 ) have through bores ( 12, 14 ) for receiving fixtures connected respectively to the body of the vehicle and to the exhaust system. The blocks ( 16, 18 ) are interconnected by three integral diagonally directed arms ( 22, 24, 26 ). Vertical vibration of the exhaust system is resisted, absorbed and damped by a combination of tension in the arms ( 22, 24, 26 ) and bending at their points of interconnection with the upper and lower blocks ( 16, 18 ). The support ( 10 ) is thus relatively resilient in this direction. However, sideways movement of the exhaust system, tending to cause movement of the lower block ( 18 ) in the direction of the axis of the lower bore ( 14 ), is firmly resisted by the arms ( 22, 24, 26 ). Such sideways movement in one direction is resisted by tensile forces in the central arm ( 22 ) and a combination of compressive and bending forces in the outer arms ( 24, 26 ), and sideways movement in the opposite direction is resisted by tensile forces in the outer arms ( 24, 26 ) and a combination of compressive and bending forces in the central arm ( 22 ).

The invention relates to a resilient support for resiliently supportinga vibratable member from a relatively rigid structure, comprising afirst end part having a front face and a rear face and being adapted forconnection to the structure, and a second end part having a front faceand a rear face and being adapted for connection to the vibratablemember, and arm means resiliently connecting the first and second endparts together such that vibration of the member relative to thestructure tends to move the first and second end parts away from andtowards each other, the arm means comprising at least a first arm madeof resilient material connected to the first and second end parts forresiliently resisting the vibrations.

Such a support is known, for example from EP-A-0 411 246. The knownsupport is usable for supporting part of the exhaust system of a motorvehicle. Such a support resists the vibrations of the exhaust systemrelative to the supporting structure of the vehicle. It is desirable,though, to arrange for such a support to have resistance also to forcesacting in a sideways direction. The invention aims to deal with thisproblem.

According to the invention, therefore, the known support ischaracterized in that the first and second end parts face in oppositedirections and the first arm is resiliently connected to the end partsand extends between corresponding faces of the end parts in a directiondiagonal to the vibration directions whereby vibrations are resisted bytension and compression in the arm and by bending where the arm isresiliently connected to the end parts and whereby movement of thevibratable member relative to the structure in directions transverse tothe vibration directions is resisted in one of those transversedirections substantially by tension in the arm and in the other of thetransverse directions by a combination of compression in the arm andbending therein.

Resilient supports embodying the invention, and for supporting anexhaust pipe in a motor vehicle, will now be described, by way ofexample only, with reference to the accompanying diagrammatic drawing inwhich:

FIG. 1 is a perspective view of one form of the resilient support is asection on the line II—II of FIG. 1;

FIG. 3 is a front view of the resilient support of FIG. 1 but showingmodification;

FIG. 4 is a perspective view corresponding to FIG. 1 but showing anotherone of the resilient supports;

FIG. 5 is a side view of the resilient support of FIG. 4; and

FIG. 6 is a view corresponding to FIG. 3 but showing a furthermodification.

The resilient support 10 of FIG. 1 is for resiliently supporting orsuspending part of the exhaust system, such as an exhaust pipe, of amotor vehicle, from the body or chassis of the vehicle. The support 10is made of elastomeric material such as rubber or other strong resilientmaterial and is preferably made by a molding process. The rubber ismolded to provide two through holes 12 and 14 for receiving stiff metalattachment hooks. Thus, a first metal hook passes through the bore 12and is attached, above the support 10, to a fixed point on the body orchassis of the vehicle. A second stiff metal hook passes through thebore 14 and extends below the support 10 into attachment to the exhaustpipe. The bore 12 in this example is circular in cross-section, whilethe bore 14 is oval. Of course, other shapes may be used instead.

The support 10 comprises upper and lower end blocks 16 and 18 which areintegrally connected together by three arms, that is, an inner arm 22and two outer arms 24 and 26. The upper and lower blocks 16,18 are ofgenerally the same external shape except that they face in oppositedirections. As is apparent from FIG. 2, the inner arm 22 extends fromthe front face 28 of the upper block 16 to the corresponding face 30 ofthe lower block 18. In contrast, the two outer arms 24,26 extend fromthe rear face 32 of the upper block 16 to the corresponding face 34 ofthe lower block 18.

In use, the support 10 operates mainly in traction in the verticaldirection, because of the force exerted by the mass of the suspendedstructure (the exhaust pipe). The arms 22,24,26 are subjected to bothtension and deflectional forces, the latter arising where the ends ofthe arms are “hinged” to the upper and lower blocks 16,18. Theflexibility of the arms thus permits a certain degree of vertical up anddown movement, and the rubber material thus helps to isolate vibrationof the exhaust system from the vehicle body and also provides gooddamping characteristics.

The exhaust system may also be subjected to forces tending to move itsideways, such forces of course being transmitted to the support 10 andthus tending to move the lower block 18 along the y axis shown in FIG. 2relative to the upper block 16. It is important that the support 10provides significant resistance to such movement in order to prevent theexhaust system coming into contact with an adjacent rigid part of thevehicle body and thus causing unpleasant “knocking”, as well as possibledamage. If such movement takes place in the Y⁺ direction, that is, inthe direction of the y axis shown in FIG. 2, the inner arm 22 will besubjected mainly to tension forces, whereas the outer arms 24 and 26will be subjected to a combination of compression and bending. If themovement takes place in the opposite direction, Y⁻, the outer arms 24,26are subjected mainly to tension while the inner arm 22 is subjected to acombination of compression and bending. In each case (that is, in eitherdirection Y⁺ and Y⁻), the arms 22,24 and 26 provide high resistance tothe sideways movement and thus help to resist knocking. The support thushas a relatively low value of K_(z)/K_(y), where K_(z) is the rigidityin the vertical direction and K_(y) is the rigidity in the transverse ory direction (Y⁺ or Y). A value of K_(z)/K_(y) close to 1 can beachieved, in contrast to more usual values of the order of 2.

In the support 10, the value of K_(z)/K_(y) is affected by the valuesfor the angles alpha₁ and alpha₂ shown in FIG. 2. The angle alpha₁ isthe angle between the horizontal and the median direction of the centralarm 22. The angle alpha₂ is the angle between the horizontal and themedian direction of the outer arm 24 (or the other outer arm 26). Thecloser alpha₁ and alpha₂ are to 90°, the greater, and the lesssatisfactory, will be the value of the ratio K_(z)/K_(y); the supportwill become closer in construction and function to known forms ofsupport which work in pure tension in the Z direction and mainly inshear in the y direction. Conversely, the smaller the value of alpha₁and alpha₂, the lower will be the value of the ratio K_(z)/K_(y).

The damping characteristics of the support are affected by the followingfactors (among others):

(a) The hardness and nature of the elastomeric material used for thesupport;

(b) The cross-section of the arms 22,24 and 26 (which can in principlebe of any shape); and

(c) the manner in which the ends of the arms are connected to the upperand lower blocks 16 and 18.

As shown in FIG. 3, elastomeric connections 36 may be integrally mouldedbetween the inner arm 22 and the outer arms 24,26.

FIG. 4 shows a modified form 10A of the support of FIG. 1. In thesupport 10A, parts corresponding to those in FIG. 1 are correspondinglyreferenced. It will be apparent that the support 10A differs from thesupport 10 in that the support 10A does not have an inner arm 22 butonly two outer arms 24 and 26, and these are directed in oppositedirections. The operation of the support 10A is generally similar tothat of the support 10. It is normally advantageous to have an oddnumber of arms (as in the support 10) because this gives the support aplane of symmetry YZ.

The two outer arms 24,26 of the support 10A can be interconnected by anintegrally moulded connection 36A as shown dotted in FIG. 5.

It may be desirable to limit the maximum possible extension of thesupports in the Z direction. This can be achieved by means of a flexiblebut inextensible belt 40 which extends around the outside surfaces ofthe blocks 16 and 18 and is located in grooves in integrally mouldedshoulders 42 and 44.

What is claimed is:
 1. A resilient support for resiliently supporting avibratable member from a relatively rigid structure, comprising a firstend part having a front face and a rear face and being adapted forconnection to the structure, a second end part having a front face and arear face and being adapted for connection to the vibratable member, thesecond end part being spaced from the first end part in a firstdirection relative to the first end part, and arm means resilientlyconnecting the first and second end parts together for movement of thefirst and second end parts away from and toward each other in the firstdirection and in a second direction diametrically opposed to the firstdirection in response to a vibration of the member relative to thestructure, the arm means comprising first, second and third arms made ofresilient material, each one of the arms being connected to the firstand second end parts for resiliently resisting the vibration, the firstand second end parts facing in opposite directions, the first and secondarms being resiliently connected to the end parts and extending betweenone of the faces of the first end part and the corresponding face of thesecond end part in a third direction diagonal to the first and seconddirections, the third arm being positioned between the first and secondarms and extending in a fourth direction diagonally opposite to thethird direction, the arrangement being such that movement of the firstand second end parts away from and towards one another in the first andsecond directions is resisted by tension and compression in the arms andby bending where the arms are resiliently connected to the end parts andsuch that movement of the second end part relative to the first end partin directions transverse to the first and second directions is resistedin one of those transverse directions substantially by tension in thefirst and second arms and in the other one of the transverse directionsby a combination of compression in and bending in the first and secondarms.
 2. A support according to claim 1, including a resilientinterconnection between adjacent arms where their diagonal directionscross over.
 3. A support according to claim 1, in which the first andsecond end parts and the arm means are integrally made of elastomericmaterial.
 4. A support according to claim 3, which is molded.
 5. Asupport according to claim 4, which is molded from elastomeric material.6. A resilient support for resiliently supporting a vibratable memberfrom a relatively rigid structure, comprising a first end part having afront face and a rear face and being adapted for connection to thestructure, a second end part having a front face and a rear face andbeing adapted for connection to the vibratable member, the second endpart being spaced from the first end part in a first direction relativeto the first end part, arm means resiliently connecting the first andsecond end parts together for movement of the first and second end partsaway from and toward each other in the first direction and in a seconddirection diametrically opposed to the first direction in response to avibration of the member relative to the structure, the arm meanscomprising at least a first arm made of resilient material connected tothe first and second end parts for resiliently resisting the vibration,the first and second end parts facing in opposite directions and thefirst ann being resiliently connected to the end parts and extendingbetween corresponding faces of the end parts in a third directiondiagonal to the first and second directions whereby movement of thefirst and second end parts away from and towards one another in thefirst and second directions is resisted by tension and compression inthe arm and by bending where the arm is resiliently connected to the endparts and whereby movement of the second end part relative to the firstend part in directions transverse to the first and second directions isresisted in one of those transverse directions substantially by tensionin the arm and in the other one of the transverse directions by acombination of compression in the arm and bending therein, the supportincluding limiting belt means for limiting the extent to which the twoend parts can move apart from each other in response to the vibration.